An air monitor at the Deutsche Bank building detected another exceedence of the element manganese on Fri., Feb. 13, several days after two previously reported exceedences.

The monitor on the northwest corner of the building found 539 nanograms of manganese per cubic meter, which is above the 500 nanograms per cubic meter considered safe. Inhaling manganese can cause neurological damage.

The Lower Manhattan Development Corp., which owns the Deutsche Bank building, reported the exceedence in an e-mailed update Feb. 20 after learning about it the night before.

The manganese likely came from a combination of welding work in the basement of the Deutsche Bank building and cement trucks for 130 Cedar St. idling near the monitor, the L.M.D.C. said.

After the L.M.D.C. found out about earlier manganese exceedences on Feb. 16, the Environmental Protection Agency stopped all basement welding work on the project, but by then, that work was already complete. No manganese exceedences have occurred since the L.M.D.C. was first notified about them, though the air-monitoring results take about five business days to come back from the lab.

The L.M.D.C. is currently decontaminating 130 Liberty St., which was damaged on 9/11 and in a 2007 fire, so workers can resume demolishing it at the end of April.